WASHINGTON — Supreme Court Justice John Paul Stevens has turned down former newspaper mogul Conrad Black's request to be freed from a Florida prison while he appeals his fraud conviction to the high court. Stevens rejected Black's plea Monday without comment. Black, a member of the British House of Lords, has served nearly 17 months of a 6 1/2-year prison term at the federal prison in Coleman, Fla. In May the court agreed to consider overturning Black's conviction in July 2007 on charges he siphoned off millions of dollars belonging to Hollinger International when he was chief executive of the media company.